1. Field of the Invention
The present invention relates generally to electronic communications, and more particularly to a system and method for generating in-phase and quadrature signals for use in a communications system or device.
2. Background Art
Modern wireless communications devices use in-phase signals and quadrature signals for modulating and demodulating communications signals. The in-phase and quadrature signals have the same frequency but differ in phase. While the in-phase signals and the quadrature signals have a phase difference of 180 degrees, the in-phase signals have a 90 degree phase difference with respect to the quadrature signals.
Well known wireless communications devices include a local oscillator (LO) for generating the in-phase signals and quadrature signals. In these wireless communications devices, the LO includes a voltage controlled oscillator (VCO) that generates a reference signal at a desired frequency and a quadrature generator that generates the in-phase and quadrature signals based on the reference signal.
One characteristic that affects the power consumption in these wireless communications devices is the phase error between the in-phase signals and quadrature signals. Specifically, the power consumption of the wireless communications device increases with the phase error between the in-phase and quadrature signals. Accordingly, an LO with a low phase error is generally desirable to limit power consumption in these known wireless communications devices. However, the implementation of the LO in these wireless communications devices to achieve low phase error (i.e., accuracy) may result in greater power consumption in the LO. Furthermore, the LO typically consumes a significant amount of power in these wireless communications devices.
In light of the above, there exists a need for a low-power quadrature generator for accurately generating in-phase and quadrature signals.